ES2337351T3 - PROCESS TO PREPARE POLYMER POLYOLS. - Google Patents

Abstract

The invention relates to a process for the batch or semi-batch preparation of a polymer polyol, which process involves (1) preparing a seed by polymerizing in a base polyol at least one ethylenically unsaturated monomer in the presence of a polymerization initiator and macromer, and in the presence of from 0.5 to 50% wt of polymer polyol heel, based on amount of polymer present in the heel compared with total amount of polymer formed, (2) adding additional ethylenically unsaturated monomer to the seed obtained in step (1) and optionally additional polyol, and (3) polymerizing the mixture obtained in step (2).

Description

Process to prepare polymer polyols.

Background of the invention

The present invention relates to a process for the preparation of polymer polyols.

Polymeric polyols are commonly used. for the manufacture of flexible polyurethane foams. The flexible polyurethane foams are widely used in numerous Applications. The main application sectors are the automotive and aeronautical industry, upholstered furniture and technical articles For example, in cars and airplanes they are used lots of seats made entirely of foam, pads for seats and fasteners for the back and head, all of them Made of flexible polyurethane foam. Other apps include the use of flexible polyurethane foam as reinforcements for carpets, rest products and mattresses, saddles motorcycle foam, joints between the body of a car and its lights, air filter flange seals for engines and insulating layers on car parts and engine parts for Reduce noise and vibration. It will be appreciated that each application specific raises its own needs on flexible foam to use. Density are important characteristics in this regard, hardness, elasticity and foam damping behavior, and in order to adapt to each application, these features they should be balanced and adjusted optimally.

A problem that is usually found in the manufacture of polymer polyols, that is, a system in which a polymer is dispersed stably in a base polyol, it is obtain a polymer polyol having a polymer content relatively high solid and a sufficiently low viscosity to facilitate handling. A polymer polyol that has this combination of properties is generally favorable for properties of the polyurethane foam produced from said polymer polyol.

The document EP-A-698628 describes a process semicontinuous to prepare a polymer polyol by polymerization of styrene and acrylonitrile in a polyether polyol in a reactor discontinuous in the presence of a preformed polymer polyol, where from 0.25 to 3% by weight of the polymer solids in the polyol Final polymer comes from the preformed polymer polyol.

The document EP-A-768324 describes a process continuous for the preparation of very stable polymer polyols, finely divided, low viscosity, where in the first stage an intermediate is prepared by reacting (1) a mixture of styrene and acrylonitrile in a mixture of (2) a polyether polyol of polyoxyalkylene and (3) a macromer in the presence of (4) a free radical initiator, (5) a solvent that has a Moderately and optionally chain transfer activity (6) A reaction moderator.

The document US-A-5223570 teaches that it is necessary a combination of continuous and semi-continuous operation to obtain grafted polymer dispersions having a distribution wide particle size without violent fluctuation of the viscosities This combination is unattractive as it requires equipment for continuous operation and equipment for operation semi-continuous

Compendium of the invention

The present invention provides a process to prepare polymer polyols that have been discovered to have a low viscosity at a relatively high solids content and which at the same time have a wide distribution of the size of particles It has been observed that a wide size distribution Particle provides better cell opening. The better opening of the cells generally leads to a decrease in the lower force for compression, which is the force necessary to compress the foam for the first time.

Therefore, the present invention relates to a process for the discontinuous or semi-continuous preparation of a polymeric polyol, comprising the process

(one)

prepare a seed by polymerization in a base polyol of at least one monomer ethylenically unsaturated in the presence of an initiator of polymerization and a macromer, and in the presence of 0.5 to 50% by weight of a polymer polyol residue, based on the amount of polymer present in the residue compared to the total amount of formed polymer,

(2)

add more monomer ethylenically unsaturated to the seed obtained in step (1) and optionally more polyol amount, and

(3)

polymerize the mixture obtained in the stage 2).

Although the use of a residue in a process semicontinuous has been described in the document EP-A-698628 and the use of a seed for a continuous process has been described in the document EP-A-768324, it was not known that he could further obtain an additionally improved polymer polyol by using a seed and a residue in a process discontinuous or semicontinuous.

Detailed description of the invention

The polyol used in the process according to the The present invention is preferably a polyether polyol, also frequently referred to as polyoxyalkylene polyols. These polyether polyols are typically obtained by making react a starting compound that has a plurality of active hydrogen atoms with one or more alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide or mixtures of two or more of these. They are suitable polyether polyols those with a nominal molecular weight in the range of 1500 to 15,000 and an average nominal functionality (Fn) of at least 2.0. Preferably, the polyol also has a high content of primary hydroxyl, suitably at least 70%. Has been found particularly advantageous to use polyols having a weight molecular in the range of 2500 to 14,000. In addition, these polyols they preferably have an Fn in the range of 2.5 to 6.0. Preferably, these polyols have a hydroxyl content. primary in the range of 70 to 100%, more preferably 75 to 95% The hydroxyl value of the polyol suitably has a value of 20 to 150 mg of KOH / g, more suitably 25 to 75 mg of KOH / g. The Examples of suitable polyols include CARADOL SC46-02, CARADOL SC36-13, CARADOL MC36-03, CARADOL SC56-02, CARADOL SC 36-11 and CARADOL MH56-03 (CARADOL It is a trademark). Even more preferably, polyol are used CARADOL SC36-13 and CARADOL SC. 36-11.

The ethylenically unsaturated monomers Suitable for preparing the dispersed polymer include vinyl aromatic hydrocarbons, such as styrene, alpha-methyl styrene, methyl styrene and several others alkyl-substituted styrenes. Of these, it is preferred the use of styrene. The vinyl aromatic monomer can be used alone or together with other ethylenically unsaturated monomers, such as acrylonitrile, methacrylonitrile, vinylidene chloride, various acrylates and conjugated dienes such as 1,3-butadiene and isoprene. They are monomers ethylenically unsaturated that prefer to be used for the purpose of the present invention styrene and acrylonitrile in a ratio molar from 30:70 to 100: 0. However, the use of styrene alone or a combination of styrene and acrylonitrile in a molar ratio of styrene: acrylonitrile from 33:67 to 67:33, resulting in polystyrene dispersed polymers and styrene-acrylonitrile copolymers (SAN), respectively.

The residue of the polymer polyol present in step (1) is preformed polymer polyol. This preformed polymer polyol can be added to the reactor or formed in situ before adding other compounds. However, it is preferred that the polymer polyol residue is the polymer polyol that remains in the reactor. An easy way to ensure that the residue is present in the reactor is to interrupt the withdrawal of the polymer polyol product before the reactor has completely emptied.

In step (1), a macromer is present. He macromer is considered a polyol containing unsaturation induced. Macromers that can be used include, but are not limitation, the reaction product of a polyol with a compound unsaturated reagent such as maleic anhydride, fumaric acid, 1,1-dimethyl-m-isopropenyl benzyl isocyanate,  isocyanatoethylmethacrylate, 2-butene-1,4-diol, 1-butene-3,4-diol, hydroxyethyl methacrylate, hydroxypropyl acrylate, methyl methacrylate, acrylic and methacrylic acid, methacrylic chloride, glycidyl methacrylate and allyl glycidyl ether. If an acid or anhydride is used polycarboxylic, it is preferred to react the unsaturated polyol with an alkylene oxide. The polyol to prepare the macromer preferably has a hydroxyl functionality of at least 3.

In the document WO-A-99/40144 a described preferred macromer. This macromer is suitable as a precursor stabilizer in a polymer polyol, and has been prepared by a process comprising reacting a polyol with an anhydride of cyclic dicarboxylic acid that does not contain any double bonds polymerizable, and then react the adduct obtained in this way with an epoxy compound that contains a double polymerizable bond. Preferably, the polyol is sorbitol which has reacted with a mixture of propylene oxide and oxide ethylene. The cyclic dicarboxylic acid anhydride is preferably phthalic anhydride. The epoxy compound is preferably glycidyl methacrylate or glycidyl acrylate. First, the adduct can be partially reacted with a compound difunctional epoxy or with greater functional functionality before if reacted with the epoxy compound containing a polymerizable double bond. In addition, the polyol can be made react with a difunctional isocyanate compound or with a greater functionality prior to the reaction between the polyol and the cyclic dicarboxylic acid anhydride. A method for preparing the macromer first comprises reacting partially the adduct with the epoxy compound containing a polymerizable double bond and then react the reaction product obtained in this way with a compound difunctional epoxy or with superior functionality or with a difunctional isocyanate compound or with functionality higher.

Preferably, the macromer has a weight molecular weight of at least 4000, preferably in the range from 5000 to 50,000.

The amount of monomers ethylenically unsaturated present during the process stages of the present invention may vary widely. At each stage of the process of according to the present invention, the amount of monomer ethylenically unsaturated will generally differ between 10 and 60% in weight based on the total weight of the base polyol, polymer, monomer or monomers and macromer. However, the amount of monomer (s) in step (1) may be greater or less depending on whether the (part of) the polyol is added along with the monomer or monomers. It is possible to have all the base polyol already present in step (1), although it is also possible to add the largest part of the base polyol in step (2) and / or (3). Preferably, the amount of monomer or ethylenically unsaturated monomers in the step (1) and / or (2) is 20 to 55% by weight, more preferably 30 at 50% by weight, based on the total weight of the base polyol, polymer, monomer or monomers and macromer.

The base polyol optionally added in the stage (2) it may be the same or it may be different from the base polyol that It was present in stage (1). Preferably, the base polyols of stage (1) and (2) are the same.

The essence of the present invention lies in the presence of the polymer polyol residue when it is made react a minor amount of monomer ethylenically unsaturated and macromer, and subsequently added and made react the main amount of monomer ethylenically unsaturated In general, a minor amount of the product remains final when the polymer polyol is removed from the reactor operated in discontinuous or semi-continuous operation. However, this amount It will generally be well below 0.5% by weight.

The amount of polymer obtained from the residue present in step (1), based on the total amount of polymer present after the reaction of the step (1), is 0.5 to 50% by weight, preferably 3 to 30% in weight, more specifically 4 to 20% by weight.

Preferably, the amount of polymer obtained in step (1) present in the final product is from 3 to 30% by weight, more specifically 4 to 20% by weight. The amount of polymer obtained from step (1) is the amount of polymer obtained from the residue and the amount of polymer formed in step (1) when the polymer is reacted obtained from the residue, the macromer, the monomer ethylenically unsaturated and the initiator. In view of the reaction substantially complete of styrene, acrylonitrile and preferred macromer, it should be assumed that styrene, acrylonitrile and said macromer are the polymer that is present in the seed. In addition, the seminal polymer will contain polymer obtained from the polymer polyol residue.

Polymerization of the monomers is carried out. by the presence of a polymerization initiator. Said initiator it is usually applied in an amount of 0.01 to 5% by weight based on the total weight of the monomers. The initiators of Suitable polymerization are known in the art and include both peroxide compounds and azo compounds. Are examples of dibenzoyl peroxide peroxides, lauroyl peroxide, t-butyl hydroperoxide, benzoyl peroxide and di-t-butyl peroxide. They are examples of azobis (isobutyronitrile) (AIBN) compounds and azobis (2-methylbutanonitrile) (AMBN).

They can also be added to the reaction medium of polymerization, or be present in it, transfer agents of chain, in small quantities. The use of agents Chain transfer and its nature are known in the art. Chain transfer agents allow control of the crosslinking that occurs between the various molecules polymeric and therefore may affect the stability of the polyol polymeric If used, a chain transfer agent is used suitably in an amount of 0.1 to 6% by weight, preferably 0.2 to 5% by weight, based on the total reagent weight. Examples of suitable chain transfer agents are 1-butanol, 2-butanol, isopropanol, ethanol, methanol, cyclohexane and mercaptans, such as dodecanothiol, ethanothiol, 1-heptanothiol, 2-octariotiol and toluenotiol.

Other compounds may also be applied, such as compounds that facilitate mixing of the various components, compounds that have a viscosity reducing effect and / or compounds that allow one or more of the components used to dissolve better in the reaction medium. An example of a compound that has a viscosity reducing effect, thus allowing better mixing of the components, is
Toluene.

The various components used in the process to prepare polymer polyols in accordance with the present The invention can be mixed together in different ways. This can achieved discontinuously or in a semi-continuous operation. In the latter case, one or more of the reactor is added continuously more compounds for a limited amount of time. The discontinuous operation and semi-continuous operation differ from the operation continues in that in the discontinuous operation or semicontinuously the product is removed from the reactor discontinuous In principle, any known way is appropriate for the purposes of the present invention. One way, for example, is to prepare the polymer polyol by dosing the monomers, the polymerization initiator and part (10-90%) of the base polyol in the reactor containing the rest of the base polyol (90-10%), the macromer and A chain transfer agent. Other ones can also be used. auxiliaries such as toluene and may be present in the supply and / or in the reactor.

The polymer polyol according to the present invention is very suitable for the preparation of foams of flexible polyurethane by reacting it with a polyisocyanate suitable in the presence of a suitable polyurethane catalyst, a suitable blowing agent and optionally substituted an agent of reticulation. This reaction is also commonly referred to as foaming Therefore, the present invention also relates to a flexible polyurethane foam that can be obtained by foaming of a composition comprising a polymer polyol as specified above herein and a polyisocyanate component.

Polyurethane catalysts are known. in the art and include many different compounds. A list wide polyurethane catalysts are given, for example, in the United States Patent Specification No. 5,011,908. For the purposes of the present invention, suitable catalysts they include tin-based catalysts, such as salts of tin and dialkyl tin salts of carboxylic acids. They are specific examples tin octoate, tin oleate, dilaureate of dibutyltin, dibutyltin acetate and diacetate of dibutyltin. Other suitable catalysts are tertiary amines, such as, for example, bis (2,2'-dimethylamino) ethyl ether, trimethylamine, triethylamine, triethylene diamine and dimethylethanolamine. Examples of tertiary amine catalysts available in the market those that are marketed under trade names NIAX, TEGOAMIN and DABCO (all trademarks). The catalyst is typically used in an amount of 0.01 to 2.0 parts by weight per one hundred parts by weight of polymer polyol (php). They are quantities Preferred catalyst of 0.05 to 1.0 php.

The use of crosslinking agents in the Production of polyurethane foams is well known. It's known that Glycol polyfunctional amines are useful for this purpose. The polyfunctional amine glycol that is used most frequently and also It is useful in the preparation of flexible polyurethane foams The present invention is diethyl amine, abbreviated normally as DEOA If used, the crosslinking agent is applied in amounts. up to 3.0 php, but quantities are more adequately applied in the 0.2 to 1.5 php range.

Suitable blowing agents include water, acetone, carbon dioxide (liquid), halogenated hydrocarbons, aliphatic alkanes and alicyclic alkanes. Due to the effect of ozone depletion of halogenated alkanes, completely chlorinated (CFC), it is generally not preferred to use this type of blowing agents, although it is possible to use them within the scope of The present invention. Halogenated alkanes, in which at least a hydrogen atom has not been substituted with a halogen atom (so-called HCFCs), have no or almost no effect of ozone depletion and therefore are hydrocarbons Preferred halogenates for use in blown foams physically. A very suitable HCFC blowing agent is 1-chloro-1,1-difluoroethane.  The use of water as a blowing agent (chemical) is also good known. Water reacts with isocyanate groups according with the well-known NCH / H2O reaction, releasing from this carbon dioxide way that causes blowing to occur. The aliphatic and alicyclic alkanes eventually developed as Alternative blowing agents for CFCs. They are examples of such n-pentane and n-hexane alkanes (aliphatic) and cyclopentane and cyclohexane (alicyclic). Be understand that the above blowing agents can be used individually or in mixtures of two or more. The quantities at which blowing agents are used are those conventionally applied, that is, between 0.1 and 5 php in the case of water and between approximately 0.1 and 20 php in the case of hydrocarbons halogenated, aliphatic alkanes and alicyclic alkanes.

In addition, other auxiliaries can also be used. well known, such as fire retardants, stabilizers foam (surfactants) and fillers. Organosilicone Surfactants they are more conventionally applied as foam stabilizers in Polyurethane production. A great diversity of these organosilicone surfactants. Usually this foam stabilizer is used in an amount of up to 5% by weight based on the reaction mixture of the polymer polyol reagent and the polyisocyanate reagent.

In a final aspect, the present invention is refers to molded articles comprising the foam of flexible polyurethane described above herein memory.

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Example one

In a one liter reactor equipped with a stirrer, heater, thermocouple, condenser, input and output means and in an atmosphere of nitrogen, they were charged, in an atmosphere of nitrogen, 692 g of a hexa-ol polyoxyalkylene which it contained 21% by weight ethylene oxide incorporated at random. He polyoxyalkylene hexa-ol had an OH value of 30 mg of KOH / g and a nominal molecular weight of 11,000. After heating at 80 ° C, 7.2 grams of anhydride were charged and dissolved phthalic (= 13 mole percent in the OH group). Subsequently added 0.66 grams of dibutyltin dilaurate (DBTDL) and 18 grams of acetone, and the temperature was increased to 120 ° C. After of 4 hours, it was established (by acid number) that the reaction is He had completed, and the acetone was removed by evaporation. Subsequently, 7.86 grams of glycidyl methacrylate (= 114 mole percent in the anhydride group) and 0.51 grams of iodide of tetrabutylammonium (TBAI) in 20 grams of isopropanol and the mixture It was reacted for 16 hours at 120 ° C.

The product obtained (macromer A) was a transparent yellow liquid that had a viscosity of 1560 mPa.s.

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Example 2

Macromer B was prepared as described in Example 1, with the difference that the polyol based on hexa-ol contained 18% by weight ethylene oxide randomly incorporated, and that had an OH value of 30 mg KOH / g The macromer B had a viscosity of 1230 mPa.s.

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Example 3 and Comparative Examples 1 Y 2

The macromers were used to prepare polyols polymeric in the experiments designated Example 3 (macromer B), Comparative Example 1 (macromer A) and Comparative Example 2 (macromer B).

A reactor equipped with a heater, a stirrer, a thermocouple and means of entry and exit and in a nitrogen atmosphere The loaded residue was part of the product of an earlier reaction

In order to prepare the seed, the reactor is they added the amounts of reagents indicated in the Table I. The base polyol was CARADOL 36-13 polyol. Subsequently, the reactor and its contents were heated to a temperature from 60 to 90 ° C. At this time, the supply is added for the seed and allowed to react at 90 ° C for between 30 and 45 minutes.

After the seed formed, the temperature was increased to 100 ° C and reagents were added additional in the course of 2 to 3 hours. 30 minutes after which will end the addition of the reagents, the polymer polyol in crude was subjected to separation under reduced pressure (10 mbar) at 120ºC

The results are indicated in Table II.

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The expression "size range of particles "refers to the width of the peak that indicates the single mode distribution of polymer particle size. He particle size range (TP interval) is defined how

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one

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where d (x%) is the diameter of particles in micrometers at which x% by volume of the particles have a smaller particle diameter. The measurements of particle sizes were on a volume basis and were performed by a laser light scattering technique with the help of a Malvern Mastersizer

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"Force for compression" provides an indication of the level of difficulty found for degrade the cell walls for the first time, called "compression" of a molded foam. The strength for compression is the force required to penetrate for the first time the central portion of a foam bag at 25% of its height original with a circular penetration tip. The strength for Compression was measured on a foam that was prepared from polyol polymer diluted with polyol to a solids content of 17% in weigh. The amount of polymer polyol is taken as 100 parts in weight. The foam formulation further comprises 3 parts by weight of water, 0.12 parts by weight of amine catalyst, 1 part by weight of diethanolamine, 0.4 parts by weight of silicone surfactant and 0.15 parts by weight of dibutyltin dilaurate. This formulation was reacted with toluene diisocyanate at an index of 105.

The abbreviation AMBN indicates azobis (2-methylbutanonitrile), which is a initiator.

Viscosity is measured according to ASTM D 4878

The average particle size is determined based on volume.

In Table II it can be seen that the process according to the present invention provides polyols stable polymers that have low viscosities (i.e. <10,000 mPa.s at 25 ° C) with a high solids content (between 37 and 45% by weight based on the total weight of the polymer polyol). In addition, the average particle size is well below 2 um, which is an indication that particles can remain in a stable dispersed condition. In addition, the Range of particle size distribution is greater than 2.0 and also the force for compression is well below 1000 N.

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TABLE 1

2

3

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TABLE 2

4

Claims (8)

1. Process for discontinuous preparation or semicontinuous of a polymer polyol, comprising the process

(one)

prepare a seed by polymerization in a base polyol of at least one monomer ethylenically unsaturated in the presence of an initiator of polymerization and a macromer, and in the presence of 0.5 to 50% by weight of a polymer polyol residue, based on the amount of polymer present in the residue compared to the total amount of formed polymer,

(2)

add more monomer ethylenically unsaturated to the seed obtained in step (1) and optionally more polyol amount, and

(3)

polymerize the mixture obtained in the stage 2).

2. Process according to claim 1, wherein the amount of polymer obtained from step (1) present in the final product is 3 to 30% by weight. 3. Process according to claim 1 and / or 2, in which the polyol has a nominal molecular weight in the 2500 to 15,000 range and an average nominal functionality (Fn) of at least 2.0 4. Process according to any one of the claims 1 to 3, wherein the ethylenically monomers unsaturated are styrene and acrylonitrile in a molar ratio of 50:50 to 100: 0. 5. Process according to any one of the claims 1 to 4, wherein the macromer is obtained by making reacting a polyol with a dicarboxylic acid anhydride cyclic that does not contain any polymerizable double bond, and subsequently reacting the adduct obtained in this way with an epoxy compound that contains a double bond polymerizable. 6. Process according to claim 5, wherein the cyclic dicarboxylic acid anhydride is anhydride phthalic. 7. Flexible polyurethane foam that can obtained by foaming a composition comprising a polyol polymeric prepared according to any one of the claims 1 to 6 and a polyisocyanate component. 8. Molded article comprising foam flexible polyurethane according to claim 7.